1. Field of the Invention
The invention generally relates to chain shuttling agents (CSAs), a process of preparing the CSAs, a composition comprising a CSA and a catalyst, a process of preparing the composition, processes of preparing polyolefins, end functional polyolefins, and telechelic polyolefins with the composition, and the polyolefins, end functional polyolefins, and telechelic polyolefins prepared by the processes.
2. Description of Related Art
Exchange or redistribution reactions of metal-ligand (e.g., alkylaluminums, aryloxyaluminums, alkylzincs, alkoxyzincs, and the like) complexes containing or derived polymerization catalysts are known. For example, see Healy M. D. et al., Sterically crowded aryloxide compounds of aluminum, Coordination Chemistry Reviews, 1994; 130(1-2):63-135; and Stapleton R. A., et al., Olefin Polymerization, Organometallics, 2006; 25(21):5083-5092.
Examples of telechelic polymers include polymeric chains containing a hydroxyl group at each chain end. Telechelic polymers can be used, for example, as rocket fuel binders and as ingredients in coatings, sealants, and adhesives.
Telechelic polymers have been prepared by a number of methods. U.S. Pat. No. 5,247,023 mentions telechelic polymers prepared from hydrocarbon polymers containing borane groups at chain ends or in polymer backbones thereof. Such telechelic polymers have a statistical (i.e., essentially random) distribution of terminal functional groups.
Examples of polyolefin polymers include polyolefin homopolymers and polyolefin block copolymers. Polyethylene (also known as polyethene or poly(methylene)), polypropylene, and poly(ethylene alpha-olefin) copolymers are examples of polyolefins (also known as polyalkenes) widely used in industry. They are desirable for making, for example, containers, tubing, films and sheets for packaging, and synthetic lubricants.
Block copolymers often have superior properties to properties of random copolymers and polymer blends. Properties, characteristics and, hence, applications of block copolymers are influenced by, among other things, how the block copolymers are made and structure and characteristics of catalysts used to prepare them.
One method of preparing block copolymers is living polymerization. Domski et al. review block copolymers prepared from olefin monomers using living polymerization catalysts (Domski, G. J.; Rose, J. M.; Coates, G. W.; Bolig, A. D.; Brookhart, M., in Prog. Polym. Sci., 2007; 32:30-92). Living polymerization processes employ catalysts having a single type of active site. Those living polymerization processes that produce high yields of block copolymers essentially involve only initiation and propagation steps and essentially lack chain terminating side reactions. The living polymerization processes are characterized by an initiation rate which is on the order of or exceeds the propagation rate, and essentially the absence of termination or transfer reactions. A block copolymer prepared by living polymerization can have a narrow or extremely narrow distribution of molecular weight and can be essentially monodisperse (i.e., the molecular weight distribution is essentially one).
Examples of block copolymers that can be made by living polymerization are olefin block copolymers (e.g., poly(ethylene alpha-olefin) block copolymers) and, especially, amphiphilic diblock copolymers. Amphiphilic diblock copolymers comprise hydrophilic and hydrophobic polymer chains. Amphiphilic diblock copolymers are useful for, among other things, surfactants, dispersants, emulsifiers, stabilizers, and antifoaming agents for aqueous mixtures; surface modifiers for plastics; and compatibilizers in polymer blends and composites (Lu Y. et al., Syntheses of diblock copolymers polyolefin-b-poly(ε-caprolactone) and their applications as the polymeric compatilizer, Polymer, 2005; 46:10585-10591). Lu Y. et al. report a discontinuous polymerization process for making polyolefin-b-poly(ε-caprolactone) diblock copolymers. The discontinuous polymerization process polymerizes a select olefin with a metallocene catalyst system and a chain transfer agent, and isolates a resulting intermediate polyolefin having a terminal hydroxyl. Then in a different reactor, the discontinuous polymerization process converts the terminal hydroxyl of the intermediate polyolefin to an aluminum alkoxide derivative with diethylaluminum chloride, and subsequently uses the aluminum alkoxide derivative as an initiator for anionic ring opening polymerization of ε-caprolactone to give the polyolefin-b-poly(ε-caprolactone) diblock copolymer.
Reporting a significant advancement in preparation of olefin block copolymers (OBCs), Arriola D J, et al. mention a catalytic system that produces olefin block copolymers with alternating semicrystalline and amorphous segments and a number of desirable material properties (Arriola D J, et al., Catalytic Production of Olefin Block Copolymers via Chain Shuttling Polymerization, Science, 2006; 312: 714-719). The catalyst system can use a chain shuttling agent to transfer polymer chains between two distinct catalysts with different monomer selectivities in a single polymerization reactor. The catalyst system produces the OBCs under an economically favorable, continuous polymerization process.
As a result, chain shuttling agents and olefin block copolymers have recently been an important area of research. PCT International Patent Application Publication Numbers WO 2005/073283 A1; WO 2005/090425 A1; WO 2005/090426 A1; WO 2005/090427 A2; WO 2006/101595 A1; WO 2007/035485 A1; WO 2007/035492 A1; and WO 2007/035493 A2 mention certain CSAs, catalyst systems, and olefin polymer compositions prepared therewith. For example, the WO 2007/035493 A2 mentions multicentered CSAs and a process that uses the multicentered CSAs to prepare olefin polymer compositions uniquely characterized by a broad, especially a multimodal molecular weight distribution. The multicentered CSAs of WO 2007/035493 A2 are compounds or molecules containing more than one chain shuttling moieties joined by a polyvalent linking group.
There is a need in the art for new chain shuttling agents, polymerization processes of using same to prepare polyolefins, end functional polyolefins, and telechelic polyolefins, and the polyolefins, end functional polyolefins, and telechelic polyolefins prepared thereby, process of making amphiphilic diblock and multiblock copolymers, the amphiphilic diblock and multiblock copolymers prepared thereby, and articles comprising the polyolefins, end functional polyolefins, telechelic polyolefins, and amphiphilic diblock and multiblock copolymers.